I notice that the Track Database has not yet been updated to allow GT mod setups to be uploaded. Is this in the pipeline? Hope so, I'm eager to find out how some drivers can be so much quicker than me at certain tracks!

I am also bewildered as to why I am so far off the pace. I am a slow poke anyway, but I am silly slow with the GTs.
I am better off with the default setups. Is everyone running with 32 psi and higher?

The setups I'm using at the moment are based on the defaults. As discussed in other threads, the default setups are pretty good for most people, being quite safe and stable. But just a few minor tweaks make them much better for my driving style:

1. Add a little negative toe at the front end. This helps turn-in.
2. Add a little more negative camber at the front end. This helps front-end grip overall.
3. Change the diff settings from 85(power)/30(coast) to 30(power)/85(coast). This will also help the car turn in to corners, but it will make it a bit trickier to drive. Take it steady until you get used to it.

I have kept all the other default settings as they were (including the high tyre pressures). The only thing I am experimenting with at the moment is changing the gear ratios to suit each individual track.

You are right, Philo, the issue with the tyre pressure is very confusing
As the readme says the tyre pressure should be at 32psi (when hot). You reach this level with the default setups, but then you dont have even tyre temperatures. Trying to reduce the pressure gives you the same temperatures at O M I, but in this case the tyres dont warm up, so they cannot build up enough grip. Moreover, the lower pressure destroys the accurate handling of your car.
So I ignore the even temperatures and only care for the correct pressure.
Apart from that, I am quite happy with the default setups. With adjusted diff ratios they are good enough for me to beat the benchmark-times on most tracks (not at Targa or Nordschleife, but that is not the fault of the setups)

EDIT: I am not so sure about the connection between lower pressure and less temperature anymore, but I assume the lower temperature weakens the stiffness of the tyre's side. With the same effect of reducing the grip.
Anyway, "Four-Wheel-Drift" suggests a maximum of 180 deg.F, so keep an eye on that.

I think i mentioned this in another thread somewhere and Bill said yes it will be done.

I'm using the default setups so far (only changing the steering ratio) and i agree they are good enough to go green at all tracks. I've still got some learning to do at the Targa to get that one green and i'll drop the fuel levels for my second run through the rank which should get Le Mans green.